I haven’t spoken to any of my “sources”, so this is pure analysis and not an attempt to add to the rumors. I believe there will be a fall release of Windows Phone 7, but that doesn’t mean there couldn’t be something true in the rumors.

One of the things that Terry Myerson (CVP of Windows Phone Engineering) and his team have proven is that they know how to do schedule driven releases. And I think they understand better than anyone out there how critical it is to have a major update to WP7 in the market to support holiday 2011 phone sales. So let me dig into things a bit and explain why I think there could be some conflicting information floating around.

There are two important developments that have occurred since the original WP7 plans were put in place. The more recent, the deal with Nokia, is very public but none of us know the details. The other is the way the Update mechanism works. Let’s talk about Nokia first.

Unlike other deals with device manufacturers the deal with Nokia is a strategic partnership in which Microsoft has clearly made commitments for changes to WP7. No doubt some of those changes have been committed for this fall to support Nokia’s desire to ship its first WP7 devices late in the year or early 2012 at the latest. I suspect that the changes for Nokia are putting pressure on the “Mango” work. As I’ve opined before, it is very difficult to do multiple releases concurrently and thus shipping a pre-Nokia “Mango” as well as a Nokia-specific release only a couple of months apart wouldn’t fly. Not only that, but if the Nokia driven changes have app developer impact then Microsoft has to get releases to developers months in advance. So I suspect Microsoft has indeed pushed out the “Mango” schedule by a month or two in order to incorporate some “must have” Nokia requirements.

Which brings us to the update strategy. When the WP7 project started I’m sure Microsoft was hoping to have the same level of control over updates that Apple has. But Apple has a very different situation. They control not only IOS, but also the hardware. And most importantly, from a carrier’s perspective, they handle support. So if the IOS 4.77 update breaks something on your phone then you go to Apple for support. WP7 and Android ship to hardware manufacturers who add to the base operating system, test it for their devices, and then ship those devices to carriers to sell them to end users. When a problem with your ATT Samsung Focus or Verizon Droid Incredible occur you call ATT or Verizon. And there is the rub with updates. If the carrier has to do the support, and they rely on the device manufacturer to add drivers and other software and then stand behind the individual devices, then both the carriers and the device manufacturers need time to do their own updates and testing before a Microsoft (or Google) update is pushed to a device. So you add months, anywhere from 2-4 I would guess, from the time Microsoft is done with an update until that update is ready to be pushed out by the carriers.

The selective carrier/OEM update dynamic, which was one of the most frustrating aspects of the old Windows Mobile world, is showing itself very painfully in the Android world. Many Android phones are running a version or two behind the current version of Android and many of those will never see an update to a newer version! What we don’t yet know is what will happen with WP7. If I had to guess it would be that Microsoft is trying to split the difference between the Apple and Android worlds on Update just as it has on so many other things with WP7. So, for example, it may have explicit agreements with both the device manufacturers and carriers and how long they can take to push an update out and when they can drop support for a particular device. Maybe they tie this to the Chassis (e.g., they’ll retire all 2010 Chassis 1 spec devices at the same time), or maybe they require something like “you must make available any updates Microsoft publishes for a device whose last date of sale is within the previous 12 months”, thus making sure customers will get at least one major update after they purchase a phone. Actually this makes a lot of sense if customers really upgrade devices every two years since it both means that customers don’t fall behind while they wait out their contract and the carrier still has a way to incent you to get a new device and contract at the two-year mark. But this is a little off topic.

Now let’s get to the fall holiday shopping season and put all this together. The big priority for device manufacturers, carriers, and Microsoft is to have a great lineup of new devices ready and in the market for the holiday shopping season. So we can expect to see the Samsung WeGotTheBestTech, HTC WeOwnYourAss, LG WeGotItToo, Dell WeveGotThisPhoneThingFigured Out, and perhaps the Nokia NowYouKnowWhoseBoss coming out in October or November at the latest. Now Samsung, HTC, LG, and Dell (as well as the carriers) have limited resources and the question you need to ask is, will those resources be focused first on getting out their new fall lineup or on getting the “Mango” update out to existing Focus, HD7, etc. customers? I think the answer to that one is pretty obvious.

When you put all this together I think a very plausible scenario is that new devices running “Mango” will ship on time in the fall of 2011. But that the push of “Mango” updates to existing devices will slip into early 2012. Anyway, this explains the conflicting rumors. Microsoft will meet its fall schedule for “Mango”, but because of the way the update process works, and the resource conflicts with shipping new devices, it may indeed be impossible for existing devices to be updated until 2012.

Only a pretty small percentage of device owners would go with a build though XDA, but I agree that enthusiasts who just can’t wait certainly would. Unfortunately the whole update thing will leave a bad taste for WP7 early adopters. The delays with NoDo already are.